Work-Item Coalescing Loops for OpenCL Context Switching
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Solution Overview
Problem
Existing methods for executing OpenCL kernel code on devices with a limited number of processing elements incur significant overhead due to context switching and inefficient use of processing resources, as they require serial execution of multiple work-items on a single processing element.
Innovation Solution
The method involves identifying code regions in OpenCL kernel code that contain synchronization barriers and enclosing them with work-item coalescing loops (WCLs), which allows for serial execution of work-items on fewer processing elements, reducing context switching overhead and optimizing resource utilization by expanding private variables and managing memory allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If work-items are executed serially on a single processing element, then context switching overhead is reduced, but processing resource utilization becomes inefficient
Solution Approach 1:
The patent segments the execution of work-items by introducing work-item coalescing loops that group multiple work-items into serial execution sequences. This segmentation allows the system to execute work-items in organized groups rather than individually, reducing context switching overhead while maintaining efficient resource utilization through structured processing.
Solution Approach 2:
The patent merges multiple work-items into coalesced execution sequences by enclosing code regions with work-item coalescing loops. This combining approach allows multiple work-items to be processed together in a coordinated manner, reducing the frequency of context switching while maintaining parallel processing benefits.
2Speed
If work-items are executed in parallel on multiple processing elements, then processing speed is improved, but context switching overhead increases
Solution Approach 1:
The patent introduces dynamic work-item coalescing loops that can adaptively group work-items based on execution requirements. These loops dynamically adjust the execution strategy by coalescing work-items into serial sequences when necessary, thereby reducing context switching overhead while maintaining parallel processing speed when beneficial.
Solution Approach 2:
The patent changes the execution parameters by introducing work-item coalescing loops that modify how work-items are scheduled and executed. This parameter change allows the system to switch between parallel and serial execution modes based on the specific requirements of the code regions, optimizing the balance between processing speed and context switching overhead.
3Adaptability or versatility
If private variables are expanded to include work-item dimensions, then variable scope and accessibility are improved, but memory allocation requirements increase
Solution Approach 1:
The patent expands private variables by adding work-item dimension indices to their scope. This dimensional expansion allows variables to be accessed and modified across multiple work-items in a structured manner, improving adaptability and versatility while enabling systematic memory management through the additional dimension of work-item identification.
Data Source
AI summary
Provided is a method of transforming program code written such that a plurality of work-items are allocated respectively to and concurrently executed on a plurality of processing elements included in a computing unit. A program code translator may identify, in the program code, two or more code regions, which are to be enclosed by work-item coalescing loops (WCLs), based on a synchronization barrier function contained in the program code, such that the work-items are serially executable on a smaller number of processing elements than a number of the processing elements, and may enclose the identified code regions with the WCLs, respectively.